Lightning-arrester.



No. 721,939. PATEN'I'EDMAR. 3, 1903.-

W. J. CHAPMAN.

LIGHTNING ARRESTER. APPLICATION FILED APR. 19, 1902.

N0 MODEL. 2 SHEETS-SHEET 1..

WM WM%4@ PHOTOJJTHQ. wasnmowu. n, c.

[No. 721,939. PATENTBD MAR. 3, 1903. W. J. CHAPMAN.

LIGHTNING ARRESTER.

APPLIOATION FILED APR. 19, 1 02. no MODEL. 2 sums-sum a.

UNITED STATES.

PATENT OFFICE.

WILIJIAM J. CHAPMAN, OF MINNEAPOLIS, MINNESOTA.

LlGHTNlNG-ARRESTER.

J'PEGIFICATION forming part of Letters Patent No. 721,939, dated March3, 1903.

Application filed April 19, 1902. Serial No. 103,735. (No model.)

To all whom it may concern: I

Be it known that 1, WILLIAM J CHAPMAN,

a citizen of the United States, residing at Minneapolis, in the countyof Hennepin and State of Minnesota, have invented certain new and usefulImprovements in Lightning-Arresters; and I do hereby declare thefollowing to be=a full, clear, and exact description of the invention,such as will enable others skilled in the art to which it appertains tomake and use the same.

My invention has for its object to provide an improved lightningarrester especially adapted for use in connection with telephone andtelegraph lines, but adapted also for more general use wherever alightning-arrester may be required. The invention is illustrated in theaccompanying drawings, wherein like characters indicate like partsthroughout the several views.

Figure 1 is a perspective view showing an ordinary telegraph ortelephone pole with line-wires supported therefrom by an ordinarycross-arm and showingalso my improved lightning-arrester inoperativeposition. Fig. 2 is a horizontal section taken centrallythrough the lightning-arrester. Fig. 3 is a front elevation of thelightning-arrester with the front plate of the case removed. Fig. 4 is afront elevation of the complete lightningarrester, some parts beingbroken away and others being shown in section; and Fig. 5 is a face viewor elevation showing in detail the so-called insulating-bridge andelectrodes secured thereto.

The numeral 1 indicates the telephone or telegraph pole, the numeral 2the cross-arm thereof, and the numeral 3 the line-wires.

The parts of the lightning-arrester proper are inclosed within a waterand air tight case afforded, preferably, by arectangular metal box at,having a flanged base which is adapted to be secured to the cross-arm 2or elsewhere by means of screws a. The outer vertical face of the caseor box a isadapted to be closed by means of a cover or plate a havingflanges a which embrace the sides of the box a, as best shown in Fig. 2.Between the flanges a of said cover a and the embraced portion of thebox a a waterproof packing or filling of putty or any other suitablematerial is placed, as indicated at a, to form a water-tight joint. Thecover a is normally held in-place by means of pins a which are driventhrough perforations in its flange a and in the embraced edge of the boxa. To

remove the cover, it is necessary to first drive electrode 0 is thussecured to the hub of the bridge I) by means of a metal bolt 0, providedat its screw-threaded end with a pair of nuts 0 Also secured to theinsulating- 'bridgeb there is, as shown, a pair of disklike electrodesf, located one on each side of the hub b As shown, the electrodes f aresocured to the said insulating-bridge by means of metal bolts f,provided at their screwthreaded ends with pairs of nuts f The faces ofthe electrodes f are serrated in two directionsthat is, are formed witha multiplicity of closely-spaced pyramidal projections or points f whichterminate close to the adjacent inner face of the electrodes 0, but arespaced apart therefrom, so that the circuit will normally be broken. Thedistance between these points and the adjacent face of the electrodes 0should be such that thecurrent which normally passes through theline-wire will not jump across, and of course a reasonable factor shouldbe allowed for safety. tration given in the drawings each of thelinewires 3 is. connected to one of the electrodes fby a wire 9, one endof which is, as shown, "clamped between the cooperating pairs of nuts fThe bolt 0, and hence the electrodes 0, are grounded by a wire 9, theupper end of which is, as shown, clamped between the nuts 0 The wires gand g are passed outward through insulating-bushings g in the bottom ofthe box a.

g indicates a wrapping of insulating material wound around the upperportions of the wires 9 g and the lower ends of the bushings g to formwater or moisture tight joints at such points.

As is evident, when one of the line-wires is In the illusstruck bylightning the abnormally high electrical charge will run along the wireuntil it comes to the first connecting-wire g, through which it willpass and leaping across from the connected electrode f to the commonelectrode 0 will pass to the ground through the bolt 0 and ground-wireg. The pointed or serrated faces of the electrodes f give a very muchgreater aggregate discharging surface than would be given by a flatsurface of the same cross-section. Furthermore, the series of verticalgrooves afforded by the said points give increased clearance forpermitting any scales or fragments which may be broken from theelectrodes from time to time either by the action of lightning or fromother causes to fall from between the electrodes to the bottom of thebox, and thereby prevent shortcircuiting between the electrodes. This isan important feature. The electrodes being inclosed in an air andmoisture tight compartment are of course protected from the action ofthe water and other elements.

It will of course be understood that the device above described iscapable of considerable modification within the scope of my invention asherein set forth and claimed. For instance, the number of electrodesfmay be increased or decreased. If increased in number, then forcooperation therewith there should be provided an electrode 0 either ofgreater length or greater width, so as to overlie or cover the severalelectrodes f. There should, of course, be one electrode f for eachline-wire.

What I claim, and desire to secure by Letters Patent of the UnitedStates, is as follows:

In a lightning-arrester, the combination with a moisture-proof casehaving a detachable cover or side, of the insulating-bridge b detachablysecured within said case and having the hub or lug b the extendedelectrode a secured to said lug b by nutted bolt 0, theelectrodesfsecured to said bridge b by nutted bolts f and provided withfaces formed with pyramidal projections, and the leads or wires 9 9connected, respectively, to said boltsf and c and passed outward throughinsulated moistureproof joints in the said case, substantially asdescribed.

In testimony whereof I afiix my signature in presence of two witnesses.

WILLIAM J. CHAPMAN. Witnesses:

ELIZABETH KELIHER, F. D. MERCHANT.

